Lighting control circuit

ABSTRACT

This disclosure relates to a series lamp circuit including a ballast resistance connected across a voltage source of E volts. Each of N lamps in the circuit is rated at E/N volts or less. When a voltage greater than E/N is sensed across a lamp, the resistance is substituted in the circuit therefor.

United States Patent [191 Maley [4 1 Jan. 16, 1973 [541 LIGHTING CONTROL CIRCUIT 323,981 8/1885 DePoele .315/297 [75] William Malay Orange 1 223 322 ii ..315/82 [73] Assignee: Techlite,lnc.,Milford,Conn.

Primary Examiner-Nathan Kaufman Flled! P 8, 1970 Attorney-DeLio & Montgomery 2 l. N 70 329 I App 57 ABSTRACT This disclosure relates to a series lamp circuit includ- [52] ggl g i ing a ballast resistance connected across a voltage [51] Int. Cl. q source of E voks. Each of N lamps in-the circuit is [58] held of search""3l5/82 297; rated at E/N volts or less. When a voltage greater than 307/1013 E/N is sensed across a lamp, the resistance is substituted in the circuit therefor. [56] References Cited 11 Claims, 3 Drawing Figures UNlTED STATES PATENTS l,749,568 3 1930 Davis "315/126 x 5i l-ll 95 B2 }55 54 l. {A if :|-|i ll 2 25} a \ZFF Zl I7 25 24 ll W J L2 l6 Hz: /4 BACK $1M PATENTEDJAH 16 I975 SHEET 1 OF 2 Ill/1 IN VEN TOR Dec/ W9 "MW ATTORNEYS PATENTEDJAH 16 1975 3.711.739

INVENTOR Wflham Modeq m K M BY pzfio W9 WW ATTORNEYS LIGHTING CONTROL CIRCUIT This invention relates to rail vehicles and more particularly relates to a head lamp system therefor.

The most prevalent types of self-propelled rail vehicles in use at the present time are diesel electric locomotives or rail cars. As a motive power system, such locomotives carry a diesel engine which drives a main generator. The main generator may be rated at 600 volts or more with a substantial power output to supply current to four or more series wound traction motors. In addition, the diesel engine either directly or through gearing will drive an auxiliary generator which furnishes a regulated low voltage output as, for example, 75 volts for control power, locomotive lighting, etc. In rail vehicles which receive power from a third rail or trolley wire, some of the power is dropped to a lower voltage for control and lighting purposes.

In locomotive head lamp systems, difficulty has long been encountered in producing head lamps which have the proper beam pattern and intensity and operate at the available voltage on the locomotive. It has been found that the best headlight beam patterns may be obtained with filaments operating at 30 volts and approximately 200 watt power consumption. Inasmuch as most all locomotives and many self propelled rail cars are equipped with two forward head lamps, the normal practice has been to have two 30 volt, 200 watt head lamps operate .in parallel from the 75 volt DC supply. This requires that a ballast resistor be connected in series with each of the lamps having a continuous loss of approximately 200 watts. While this type of circuitry has been widely used on rail vehicles, it presents several problems. Specifically, the two parallel circuits require double the amperage of a single lamp, the ballast resistors give off a substantial amount of heat which must be dissipated together with the heat from other electrical elements in the control lockers and cabinets.

In view of these problems in locomotive head lamp circuits, this invention provides 'a head lamp circuit such that in normal operation the two lamps will operate in series, while a ballast resistance is provided to be inserted in the circuit in the event of a lamp failure. This alleviates a serious problem of the locomotive builder in the dissipation of a large amount of heat in the control cabinets and lockers. A circuit embodying the invention is further arranged such that should a head lamp burn out or fail, such failure is sensed and-a ballast resistor immediately inserted in circuit with the remaining lamp. A further advantage of this invention is that the headlight control switch and all associated equipment with it can be sized for approximately onehalf the current required for two lamps inparallel in the presently used arrangement.

A further advantage is found where a backup light is incorporated on a locomotive; it may be placed in the normal head lamp circuits to substitute for one of the normal headlights. This means that if the locomotive is in yard service and is operating at a slow speed, it can have both a forward and a reverse light on at the same time so that both lights act as a heat sink and no ballast resistor is necessary.

Briefly stated, the invention in one form thereof comprises a series circuit of the two head lamps including a ballast resistance whichmay be mounted in heat exchange relationship to the head lamp housing so that such housing may act as a heat sink. A normally closed short circuit or by-pass path is provided about the ballast resistance. The ballast resistance is inserted in the head lamp circuit only if one of the lamps should fail. A voltage sensing network is disposed across each head lamp and is effective to sense failure of the lamps. If either lamp should fail, the entire supply of voltage will appear across the lamp. This is sensed and circuit means operated to prOvide a by-pass circuit about the failed lamp, and insert the ballast resistance into the circuit so that the source still sees the same impedance. Only at this time will the circuit provide any substantial heat loss.

An object of this invention is to provide a new and improved head lamp circuit for electric rail vehicles.

A further object of this invention is to provide a circuit of the type described wherein the two head lamps normally operate in series and require no ballast resistor.

A further object of this invention is to provide a circuit of the type described in which failure of one of the lamps is sensed and a ballast resistance is immediately inserted in the circuit.

A still further object of this invention is to provide a head lamp control circuit of the type described wherein the backup head lamp may'also be utilized without requiring dissipation of heat in a ballast resistance under normal conditions.

The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of this specification. However, the invention both as to its organization and operation, together with further objects and advantages thereof, may best be appreciated by reference to the following detailed description taken in conjunction with the drawings in which:

FIG. 1 is a front elevation of a typical rail vehicle head lamp housing;

FIG. 2 is a sectional view seen in the plane of lines 2-2 ofFlG. Land FIG. 3 is a schematic diagram of a circuit embodying the invention.

In the following description, it will be understood that the term head lamp" will refer to the locomotive headlights when they are mounted for illumination in the normal forward direction of operation of the locomotive or when mounted to, the reverse end, as may be found in the so-called road switchers or general purpose locomotives.

In FIG. 1 is illustrated a housing 1 which is shown as attached to one end 2 of a rail vehicle. The housing I is secured to the rail vehicle as by means of a plurality of bolts 3 and supports a pair of head lamps L1 and L2 therein. A pair of ring-like members 4 are hinged to the housing as shown at 5 and secure the rim 6 of the head lamps against an annular resilient member 7. The members 4 may be swung open by releasing pivotal hinge bolts 8 to allow the placement of the head lamp. A support member 9 mounts a resistance element 17 in electrically insulated by good heat exchange relationship with housing I. The housing member is preferably formed of material having a high degree of thermal conductivity such as aluminum. The heat generated by the lamps and also ballast resistance 17, when in use, may be readily dissipated. It will be appreciated that the housing be in g mounted on the end of a rail vehicle will be subject to high velocity impingement of air thereon which will serveto rapidly dissipate any heat conveyed to the housing by the lamps or resistance.

Referring now to FIG. 3, there is shown a lighting control circuit for lamps L1 and L2 and also ,for a backup lamp L3 (not shown in FIGS. 1 and 2). Lamp L3 may be mounted in a similar but single unit housing.

A direct current auxiliary' generator AG as found on the well-known diesel electric locomotive is driven through suitable gearing from the diesel engine (not shown). Such generator will be connected in parallel with a battery supply B generally rated at 64 volts together with a voltage regulator R. It will be understood that when the invention is embodied on other types of rail vehicles, the lighting power source may take other forms, and the regulated voltage may be a different value. A network embodying the invention is connected across the auxiliary generator which, by way of example, may provide a regulated 75 volt output. The positive side of the generator is connected to a selector switch 11 over a line 12 whichmay have terminals 11a 11d, one of which is an OFF position, a second a DlM position, a third forward head lamp ON position, and the fourth a backup head lamp ON position. Terminals 1 lb and 11c are both connected to terminal 15 with a dimming resistor 13 in series with contact 11b. From either terminal 11b or 11c, a series circuit may be traced to head lamp L1, a ballast resistor 17 in line 16, head lamp L2, terminal 24, voltage dropping resistor 19 in line 18, and return to the negative side of the auxiliary generator or ground. Connected across terminals 20 and 21 of lamp L1 is a voltage sensing or detection network 22. Connected across terminals 23 and 24 of lamp L2 is a voltage sensing network 25. The sensing networks 22 and 25 contain relays A and B, respectively, each as shown having a pair of normally open A3, A4 and B3, B4 contacts and a pair of normally closed contacts A1, A2, and B1, B2, respectively.

With this arrangement, it will be noted that with both head lamps L1 and L2 operating, the ballast resistor 17 which is rated to have the same resistance and dissipate the same wattage as one of the head lamps is by-passed from terminal 21 through normally closed contacts B2 and A2 to terminal 23. In the example given, if the head lamps L1 and L2 are rated at volts and the applied voltage is 75 volts, it will only be necessary to drop l5 volts across resistor 19.

It will further be noted that if selector switch 11 is placed on its contact 11d, a circuit will be established through backup head lamp L3 and forward head lamp L2. With this operation, even though the locomotive may be operating in a reverse direction, the housing for lamp L2 is used as a heat sink and there is no undue requirement forheat dissipation within the locomotive cab.

The voltage sensing circuits 22 and 25 further include a voltage threshold sensitive device such as zener diodes 27 and 28, respectively. The operating voltage of each relay in series with the zener diodes is selected sothat the sum of its operating voltage and the breakdown voltage of the zener is slightly less than the voltage across the circuit 10, but greater than the battery voltage.

Following the numerical example previously given, the relays A and B may have operating voltage ratings of 30 volts, the zeners have a breakdown voltage of 40 volts and the impressed voltage from the auxiliary generator is volts. The relays thus have the same operating voltage as the rating of the lamps.

Assume now that the selector switch 1 1 is on contact 11c and head lamps L1 and L2 are illuminated. If for any reason head lamp L2 should fail, there will be an open circuit between terminals 23 and 24 and there will be a voltage difference of 75 volts thereacross. This voltage, however, is impressed across relay B and zener diode 28 through normally closed contacts Al and B2. This will break down the zener diode 28 and energize relay B which will open its normally closed contact B1 and B2 and close its normally open contacts B3 and B4. When contact B2 opens, it opens the normally closed short circuit around ballast resistor 17.

The closing of the normally opened contact B4 will short out zener diode 28 and also latch in relay B across terminals 21 and 24 through contacts A1 and A2. If for any reason the filament in lamp L2 is broken or severed and it should momentarily make connection it will not affect the established circuit inasmuch as there is a dead short through the closed contacts B3 and B4 around terminals 23 and 24.

Even if there should be a failure in zener diode 27 in circuit with relay A, there would be no effect on the circuit inasmuch as contacts B1 and B2 are open.

The established circuit will now remain energized until the selector switch is turned to an OFF position. If the circuit is re-energized before the defective lamp is changed,'the same sequence will follow and lamp Ll will be illuminated. As soon as the defective lamp'is replaced, the system will go back to its normal operation without any adjustment of the control.

Again, assuming normal operation with both head lamps L1 and L2 is operative, if head lamp L1 should fail, the line voltage will be applied across relay A and zener diode 27 by virtue of their connection across terminals 20 and 21 through normally closed relay contacts B1 and A2, zenerdiode 27 will break down and relay A will become energized, opening its normally closed contacts A1 and A2 which opens the short circuit across ballast resistor 17. Simultaneously therewith, normally open contacts A3 and A4 are closed providing a short circuit about lamp L1 and establishing a current path through ballast resistance 17. Also contact A4 provides a short circuit about zener diode 27 and latches in relay A. The circuit path is now from terminal 20 through contacts A4 and A3 to terminal 21 and through ballast resistance 17 and lamp I When the locomotive is of the type equipped with a backup head lamp, such head lamp may be connected between contact 11c and point 21. In this mode of operation, with selector switch 11 on contact 11d the circuit is through lamp L3, terminal 21, contacts B2, A2, terminal 23 and lamp L2 and no heat dissipating ballast resistance is in circuit.

Even in this mode of operation, if lamp L2 should fail, such failure would be sensed by detecting network 25 and ballast resistance substituted for lamp L2 in the manner previously described.

The only requirements of the circuits are that if the potential applied at switch 11 is rated at E volts, the voltage rating of the lamps is E/N or less; where N is the number of lamps and each zener diode orother voltage threshold sensing element together with its associated relay must be sensitive at a voltage greater of E or less.

It will be apparent that the network provided is voltage sensitive and requires no current sensing units, and in normal operation has no requirements for dissipation of large amounts of heat. Even when a ballast resistance is rendered operative, the heat generated thereby is transferred to a heat sink which rapidly dissipates the generated heat.

It may thus be seen that the objects of the invention set forth as well as those made apparent from the preceding description are efficiently attained. While preferred embodiments of the invention have been set forth for purposes of disclosure further embodiments of the invention as well as modifications to the disclosed embodiments which do not depart from the spirit and scope of the invention may occur to others skilled in the art. Accordingly, the appended claims are intended to cover all embodiments and modifications of the invention which do not depart from the spirit and scope of the invention.

What is claimed is:

1. In a rail vehicle head lamp system comprising two lamps connected in circuit with a voltage source having a voltage E, where the lamps are rated at 13/2 volts or less; the improvement comprising; a series circuit containing said lamps and a ballast resistance rated to dissipate substantially the same power as either of said lamps, circuit means normally bypassing said resistance so that there is no voltage drop thereacross, first and second voltage sensing means, each of said sensing means being connected across one of said lamps and arranged to sense a voltage thereacross greater than E/2, a normally open circuit about each of said lamps and first and second switching means responsive to said first and second sensingmeans respectively detecting a voltage greater than E/2 for opening the resistance bypass circuit and closing the normally open circuit about the lamp where a voltage greater than E/2 is sensed.

2. The improvement of claim 1 wherein each of said voltage sensing means comprises a voltage threshold sensing device and a switch controlling device.

3. The improvement of claim 2 further including a third lamp in series with said resistance and one of said two lamps, and selector means for applying the voltage E across said third lamp, said one of said first and second lamps and said resistance.

4. The improvement of claim 2 wherein said switch controlling device controls a plurality of switches effective to create a by-pass circuit about the lamp where a voltage greater than E/2 is sensed, shunt said voltage threshold sensing means and open the circuit means normally by-passing said resistance.

5. The improvement of claim 4 wherein said switch controlling device is a relay and its switches are effective to place said relay in the by-pass circuit around its associated lamp.

6. The improvement of claim 2 wherein said voltage threshold sensing device is a zener diode having a voltage breakdown value reater than E/2.

7. The lmprovemen of claim 5 wherein each of said relays has a normally closed contact in said resistance by-pass circuit.

8. The improvement of claim 5 wherein each of said relays includes a normally closed contact in the voltage sensing circuit of the other relay.

9. In a lighting system comprising two lamps connected in circuit with a voltage source having a voltage E, where the lamps are rated at E/2 volts or less; the improvement comprising; a series circuit containing said lamps and a ballast resistance rated to dissipate the same power as one of said lamps, first circuit means normally by-passing said resistance, first and second voltage sensing means connected across each of said lamps arranged to sense a voltage thereacross greater than E/2, and means responsive to said sensing means detecting a voltage greater than E/2 for opening the bypass circuit and providing a short circuit about the lamp where a voltage greater than E/2 was sensed, said first circuit means including first and second normally closed contacts controlled by first and second relays, respectively, said first and second relays being part of said first and second voltage sensing means respectively, each of said relays including a plurality of other contacts effective to close the by-pass circuit and latch the relay, open said one of said first and second contacts in said first circuit means, and disable the other of said voltage sensing means.

10. The lamp system of claim 1 comprising a housing mounting said lamps, said resistance being mounted in close proximity and heat exchange relation with said housing, said housing being constructed of a material having a high coefficient of thermal conductivity, said housing being mountable to said vehicle to expose at least one surface thereof to the ambient atmosphere.

11. In a vehicle lighting system comprising two head lamps designed to operate at a predetermined voltage, a housing mounting said lamps, said lamps receiving energy in series from a vehicle mounted source having a voltage greater than the predetermined voltages of each of said lamps; a ballast resistance in series circuit with said lamps, circuit means connecting said resistance and said lamps to said voltage source, said resistance being mounted in close proximity and heat exchange relation with said housing, said housing being constructed of a material having a high coefficient of thermal conductivity, said housing being mounted to said vehicle to expose at least one surface thereof to the ambient atmosphere, said circuit means including a circuit path normally bypassing said resistance so that there is no voltage drop thereacross, sensing means for sensing failure of either of said lamps and switching means responsive to said sensing means sensing failure of either of said lamps adapted to open said bypass circuit and provide a further bypass circuit about the failed lamp, and establish a series circuit through said resistance and the remaining lamp. 

1. In a rail vehicle head lamp system comprising two lamps connected in circuit with a voltage source having a voltage E, where the lamps are rated at E/2 volts or less; the improvement comprising; a series circuit containing said lamps and a ballast resistance rated to dissipate substantially the same power as either of said lamps, circuit means normally bypassing said resistance so that there is no voltage drop thereacross, first and second voltage sensing means, each of said sensing means being connected across one of said lamps and arranged to sense a voltage thereacross greater than E/2, a normally open circuit about each of said lamps and first and second switching means responsive to said first and second sensing means respectively detecting a voltage greater than E/2 for opening the resistance bypass circuit and closing the normally open circuit about the lamp where a voltage greater than E/2 is sensed.
 2. The improvement of claim 1 wherein each of said voltage sensing means comprises a voltage threshold sensing device and a switch controlling device.
 3. The improvement of claim 2 further including a third lamp in series with said resistance and one of said two lamps, and selector means for applying the voltage E across said third lamp, said one of said first and second lamps and said resistance.
 4. The improvement of claim 2 wherein said switch controlling device controls a plurality of switches effective to create a by-pass circuit about the lamp where a voltage greater than E/2 is sensed, shunt said voltage threshold sensing means and open the circuit means normally by-passing said resistance.
 5. The improvement of claim 4 wherein said switch controlling device is a relay and its switches are effective to place said relay in the by-pass circuit around its associated lamp.
 6. The improvement of claim 2 wherein said voltage threshold sensing device is a zener diode having a voltage breakdown value greater than E/2.
 7. The improvement of claim 5 wherein each of said relays has a normally closed contact in said resistance by-pass circuit.
 8. The improvement of claim 5 wherein each of said relays includes a normally closed contact in the voltage sensing circuit of the other relay.
 9. In a lighting system comprising two lamps connected in circuit with a voltage source having a voltage E, where the lamps are rated at E/2 volts or less; the improvement comprising; a series circuit containing said lamps and a ballast resistance rated to dissipate the same power as one of said lamps, first circuit means normally by-passing said resistance, first and second voltage sensing means connected across each of said lamps arranged to sense a voltage thereacross greater than E/2, and means responsive to said sensing means detecting a voltage greater than E/2 for opening the by-pass circuit and providing a short circuit about the lamp where a voltage greater than E/2 was sensed, said first circuit means including first and second normally closed contacts controlled by first and second relays, respectively, said first and second relays being part of said first and second voltage sensing means respectively, each of said relays including a plurality of other contacts effective to close the by-pass circuit and latch the relay, open said one of said first and second contacts in said first circuit means, and disable the other of said voltage sensing means.
 10. The lamp system of claim 1 comprising a housing mounting said lamps, said resistance being mounted in close proximity and heat exchange relation with said housing, said housing being constructed of a material having a high coefficient of thermal conductivity, said housing being mountable to said vehicle to expose at least one surface thereof to the ambient atmosphere.
 11. In a vehicle lighting system comprising two head lamps designed to operate at a predetermined voltage, a housing mounting said lamps, said lamps receiving energy in series from a vehicle mounted source having a voltage greater than the predetermined voltages of each of said lamps; a ballast resistance in series circuit with said lamps, circuit means connecting said resistance and said lamps to said voltage souRce, said resistance being mounted in close proximity and heat exchange relation with said housing, said housing being constructed of a material having a high coefficient of thermal conductivity, said housing being mounted to said vehicle to expose at least one surface thereof to the ambient atmosphere, said circuit means including a circuit path normally bypassing said resistance so that there is no voltage drop thereacross, sensing means for sensing failure of either of said lamps and switching means responsive to said sensing means sensing failure of either of said lamps adapted to open said bypass circuit and provide a further bypass circuit about the failed lamp, and establish a series circuit through said resistance and the remaining lamp. 